Current converting system



18, 1939- F. F. Hu'rcHmsoN 2,166,155

CURRENT CONVERTING SYSTEM Filed Aug. 29, 1938 1 J J J J J 1 I 1 1 1 1 my 4! J 86 87 1 i 1 FEN QN Fffuf' ffz zsow BY 1 as 89 ATTORNEY Patented July 18, 1939 UNITED STATES PATENT OFFICE Fenton F. Hutchinson,

San Francisco, Calif., as-

signor to Kohler & Chase, 'San Francisco, Calif., a corporation of California Application August 29 6 Claims.

The invention, in general, relates to means for supplying alternating current from a direct current source. More particularly, the invention relates to a current converting system affording distribution or allotment of the current at predetermined time intervals in predetermined quantities.

In all current converting systems presently in use, it is the conventional practice to make use of external resistance of some character, such as resistors, condensers, reactances, or the like, to take care of load variations. Moreover, the selection and arrangement of such resistors or combination of resistors and condensers has effective results in the production of desired wave forms for meeting various industrial applications. Under certain load conditions, a relatively high degree of efficiency maintains in many current converting systems while under load conditions Where the variations are appreciable the eificiency of the system materially decreases because the resistors and condensers employed cannot withstand such extreme load variations, and must be frequently replaced. Moreover, it is customary to design resistors and condensers for use with fairly constant loads as well as for effecting desired wave forms under such conditions of operation. Due to the use of such designed resistors and condensers, relatively wide variations in load result in distortion of the wave form and unsatisfactory performance.

It is a primary object of my invention to provide a current converting system which affords eflicient performance under relatively Wide load variations Without the use of external resistance.

Another object of the invention is to provide a current converting system of the indicated character embodying means for allotting or distributing current at predetermined time intervals and in predetermined quantities regardless of load variations.

A still further object of my invention is to provide a system of the aforementioned character which also is adapted to produce predetermined and variable current and voltage wave forms without the use of external resistance.

Other objects of the invention, together with some of the advantageous features thereof, will appear from the following description of a preferred embodiment of my invention which is illustrated in the accompanying drawing. It is to be understood that I am not to be limited to the precise embodiment of the invention shown in the drawing, as my invention, as defined in the 1938, Serial No. 227,332

appended claims, is adaptable for embodiment in a plurality and variety of forms.

Referring to the drawing:

The single figure is a diagrammatic view of a preferred embodiment of the invention.

In its preferred form, the current converting system of my invention preferably comprises a source of direct current, means for supplying alternating current from said direct current source including an electrical circuit comprising a commutator divided into a plurality of segments electrically insulated from one another and electrically connected together in pairs, a rotatable brush connected to one side of said direct current source and adapted to engage successive segments of said commutator at predetermined time intervals, together with a transformer having a mid-point tap electrically connected to the other side of said direct current source and having a plurality of taps on each side of said mid-point tap dividing said transformer into an equal number of sections on each side of the center thereof, and electrical conductors between said segments of said commutator and said plurality of taps on said transformer for distributing the current in predetermined quantities at predetermined time intervals' upon rotation of said brush.

As illustrated in the accompanying drawing, I provide a direct current source II, such as a conventional storage battery, together with an electrical circuit including a commutator I2 divided into a plurality of segments I3, preferably an even number, which are electrically insulated from one another in the usual manner by suitable strips ll of insulation material. It is to be appreciated that in applications of the converter of my invention to relatively light loads a converter having a commutator with fewer segments I3 may be used and. a single brush employed rather than the number of segments shown in the commutator illustrated in the drawing and rather than the two brushes shown. In the particular embodiment of the invention shown in the draw ing, I have divided the commutator into forty segments I3 and arranged the same in quadrants I6, II, I8 and I9, as indicated by the reference letters AB, BC, CD and DA, and I have also provided a separator bar 2 I, which conveniently may be termed adead bar, between each quadrant of segments, although these dead bars are not essential.

In accordance with the invention, one side of the direct current source II is electrically connected by a lead 22 to the commutator brushes 23 which preferably are mounted on the inside of the annulus containing the segments I3 and on a metal block 24 keyed or otherwise secured to a driven shaft 28. It is, of course, optional to mount the brushes inside of the annulus as they can be mounted outside thereof, if desired, with equal results. The mounting of brushes 23 is such that the brushes engage segments I3 of the commutator under the action of centrifugal force upon rotatable movement of the brushes when the shaft 26 is rotated. Suitable pins are provided on metal block 24 to limit the inward movement of brushes. The other side of the direct current source I I is electrically connected by means of a lead 2'! to a mid-point tap 28 of a transformer 29 which preferably is a conventiona1 metal core transformer of the standard type having the core 3I built up of laminations to reduce eddy currents to a minimum.

As illustrated, I divide transformer 29 into a plurality of sections, preferably equal in number on each side of mid-point tap 28, by tapping the transformer as at 32, 33, 34, 36, 31, 38, 39 and 4|. In the particular embodiment of the invention illustrated, I have provided five sections on each side of the center tap 28 but it is to be understood that I am not to be limited to the number of sections in which the transformer may be divided nor to the number of segments into which the commutator I2 may be divided. The various sections of transformer 29 are electrically connected to the segments I3 of the commutator I2,

by groups, as shown. Thus, the first segment I3 of quadrant I6 of the commutator, i. e., the first segment to the right of the top center of the commutator, as indicated by the reference letter A, is connected by a lead 42 to one end 43 of transformer 29 and such segment I3 is also connected, by means of a'conductor 44, to the last or tenth segment I3 of quadrant I6. Moreover, I provide a jumper bar 46 leading from such last or tenth segment I3 of quadrant I6 to lead 42 thus electrically connecting the first and tenth segments I3 of quadrant I8 of the commutator, as a pair, to the end 43 of the transformer 29. Similarly, I provide electrical connections joining the second and ninth segments l3 of quadrant IB ofthe commutator I3 to the transformer, but to a section tap thereof rather than to the end 43. As shown, I provide a lead 4! connecting the second segment of quadrant I8 to section tap 41 of the transformer; a conductor 48 con.- necting such second segment to the ninth segment of quadrant I6; and a jumper bar 49 connecting the ninth segment to the lead 41 so as to connect the second and ninth segments I3 of quadrant III of the commutator, as a pair, to the transformer 29 at section tap 41. Likewise, I electrically connect the third and eighth segments of quadrant I6, as a pair, to the transformer 29. These connections include a lead 5| from the third segment to a. section tap 39 of the transformer; a conductor 52 joining the third segment with the eighth segment; and a jumper bar 53 from the eighth segment to lead 5| Similarly, the fourth and seventh segments of quadrant I8 of the commutator are electrically connected, as a pair, to the transformer 29. The connections for the fourth and seventh segments include a lead 54 connecting the fourth segment to section tap 38 of the transformer; a conductor 56 joining the fourth and seventh segments; and a jumper bar 51 leading from the seventh segment to the lead 54. The fifth and sixth segments of quadrant I6 are also electrically connected as a pair to the transformer and, accordingly, I provide a lead 58 connecting the fifth segment to section tap 3! of the transformer; and a jumper bar 59 connecting the sixth segment of quadrant I8 to the lead 58, there being no need for a conductor between the fifth and sixth segments as the brush 23 is sufficient in width to span the segments and effect the electrical connection. Thus, the fifth and sixth segments I3 of quadrant I6 of the commutator also are connected, as a pair to the transformer 29 through section tap 3! thereof.

In a like manner, the segments I3 of quadrant 5'9 of the commutator I2 are electrically connected, in pairs, to the transformer 29 by sections. Quadrant III of the commutator conveniently is marked out in the drawing by the reference letters DA. The first segment of quadrant I9, i. e., the segment to the left of the top center of the commutator indicated by reference letters A, is

electrically connected by means of a lead SI to the end 82 of the transformer 28; a conductor 63 joins the first segment to the tenth segment of quadrant I9; and a jumper bar 84 joins the tenth segment to lead GI. Similarly, the second segment and ninth segment of quadrant joined, as a pair, to a. section of transformer 29. To effect this connection, I provide a lead 88 from the second segment to section tap 32 of the transformer; and a jump bar 88 connecting the ninth segment to lead 68. eighth segments of quadrant I9 are electrically connected, as a pair, to another section of transformer 29. The connections for this pair include a lead 89 from the third segment to section tap 33 of the transformer; a conductor II joining the third and eighth segments; and a jump bar H from the eighth segment to the lead 89. Similarly, the fourth and seventh segments of quadrants I9 are electrically paired together and connected to a section tap of the transformer. The electrical connections for this pair of segments include a lead I3 from the fourth segment to section tap 34 of the transformer; a conductor l4 joining the fourth to the seventh segment; and a jump bar I6 leading from the seventh segment to the lead 73. The fifth and sixth segments of the quadrant I9 also are electrically connected, as a pair, to the transformer and, to effect this result, I provide a lead II from the fifth segment to section tap 38 of the transformer and a jump bar I8 from the sixth segment to the lead TI, there being no need of a conductor between the fifth and sixth segments as the brush 23 spans the two segments and electrically connects the same.

The foregoing connections would be all that would be required for a twenty segment arrangement with one brush. However, in the embodiment of the invention illustrated in the drawing wherein forty segments with two brushes are depicted, I arrange the system so that the segments I3 of diametrically opposite quadrants are grouped in pairs. Thus, the segments of quadrant I8 are electrically grouped in pairs with pairs of segments I3 of quadrant I 6, while the segments of quadrant I! are electrically grouped in pairs with pairs of segments of quadrant I9. Accordingly, I provide a lead I9 which joins the first and tenth segments, as a pair, of quadrant I8 of the commutator to jump bar 48 or, if desired, directly with lead 42 which connects the first and tenth segments of quadrant IE to the end 43 of the transformer. Similarly, I provide a lead 8| connecting the second and ninth segments of quadrant I8, as a pair, with the connections that join the second and ninth segments of I9 are Likewise, the third and :1.

til

quadrant l6, as a pair, to section tap 4| of the transformer, lead 8|, in the embodiment shown, being connected to jump bar 49. Likewise, the third and eighth segments of quadrant [8 are electrically connected as a pair, by means of lead 82 from such eighth segment to jumper bar 53, to the paired third and eighth segments of quadrant |8 which are connected to section tap 39 of the transformer 29 as above described. Similarly, lead 83 from the seventh segment of quadrant l8 of the commutator to lead 54 groups the paired fourth and seventh segments of quadrant I8 with the paired fourth and seventh segments of quadrant I6 which are electrically connected to tap 38 of the transformer. Likewise, the lead 84 from the sixth segment of quadrant I8 to the jump bar 59 groups the paired fifth and sixth segments of such quadrant [8 with the paired fifth and sixth segments of quadrant l6 which are electrically connected with section tap 31 of the transformer 29.

In a like manner, the segments of quadrant H are paired together and grouped with the paired segments of quadrant !9 of the commutator. This grouping is effected through leads 86, 81, 89 and 91; lead 85 joining the first and tenth segments of quadrant IT, as paired, to jump bar 64 which connects the first and tenth segments of quadrant 19 to the end 52 of transformer 29 through the lead 6| Similarly, lead 8'! joins the ninth segment of quadrant IT to the jump bar 68 for electrically connecting the second and ninth segments of such quadrant IT, as a pair, to the paired second and ninth segments of quadrant |9 which, in turn, are electrically connected through lead 55 to section tap 32 of the transformer. Likewise, the lead 88 from the eighth segment of quadrant I! of the commutator to jump bar 12 groups the paired third and eighth segments of such quadrant I! with the paired third and eighth segments of quadrant l9 which, in turn, are electrically connected through lead 69 and jump bar 12 to section tap 33 of the transformer, as above described. Similarly, lead 89 from the seventh segment of quadrant I! to the lead 13 groups the paired fourth and seventh segments of such quadrant I! with the paired fourth and seventh segments of quadrant l9, the latter being electrically connected to section tap 34 of the transformer through the lead 13 and jump bar 18. Likewise, the paired fifth and sixth segments of the quadrant I! of the commutator are grouped with the paired fifth and sixth segments of quadrant I9 through lead 9| which connects to lead H, the latter, together with jump bar '18, connecting the paired fifth and sixth segments of quadrant IS with section tap 33 of the transformer.

It may be observed that in accordance with standard practice, an alternating load circuit may be directly connected, as by means of leads 92 and 93, to the ends 43 and 62, respectively, of transformer primary 29. Or, if desired, a secondary coil 94 may be incorporated into the transformer, for stepping up or stepping down the voltage to predetermined values, and leads 55 and 97 employed for connecting the secondary to an alternating current load circuit.

In explanation of the mode of operation of the system of my invention, it may be assumed that shaft 28 is driven at a constant speed and that the shaft rotates in a clock-wise direction. With switch 98 closed, it will be clear that when brushes 23 initially engage the first segment of quadrant l6 and the tenth segment of quadrant l8 of the commutator, a direct current will flow in the established circuit from the direct current source ll through the brushes 23, thence through the engaged segments I3 and through one-half of the transformer 29 from end 43 thereof to the mid-point tap 28 thereof, and thence back to the other side of the direct current source through lead 21. As the brushes continue to rotate in the clock-wise direction, first one section after another of one-half of transformer 29 is cut out of the circuit thus established and then such sections are placed back in the circuit, the current traveling always toward the mid-point of the transformer when operations are on one-half of the transformer. After brushes 23 leave the segments of the quadrants IB and I8 of the commutator and engage the segments of quadrants I1 and 19, the circuit is established through the other one-half of transformer 29 from. one side of the direct current source ll through brushes 23, the above described electrical connections to the end 62, of the transformer, through the transformer to the mid-point tap 28 and thence through lead 21 back to the other side of the direct current source. As the brushes 23 continue to rotate and successively engage the segments of quadrants H and I9, first one section after another of one-half of the transformer are cut out successively and then cut back into the circuit, the

current always traveling from end 62 of the transformer toward the mid-point tap 28 when the brushes are engaging the segments l3 of quadrants l1 and [9 of the transformer. Thus,

with the brushes 23 rotating at a constant speed,-

current flows alternately through transformer 29, first in one direction from one end thereof to the mid-point 28 thereof and then in the other direction from the other end of the transformer to the mid-point thereof, and, at the same time, successively cutting out and cutting in the different sections on each side of the center of the transformer as above described. In addition to the supplying of alternating current, direct current also flows in the circuit which is in phase with the alternating current.

Since the current is distributed or allotted by sections, or by commutator segments, at predetermined time intervals, it will be clear that even though the'voltage in the circuit rises as each section of the transformer is cut out and lowers again as the sections are cut back in again during each alternation, the circuit will not be shorted since no coils are bucked and since the current always flows toward the center tap of the transformer. It also will be clear that, with the arrangement shown, the direct current varies in direct proportion to the value of the alternating current. Since I have eliminated the need for external resistance, the system will function with increased efficiency.

It is possible, with the current converting system. of my invention as illustrated, to obtain desired types of wave forms without the use of external resistance. By varying the number of windings per section of the transformer and by varying the number of windings in each section, it is clear that Wave forms can be predetermined. The particular type of wave form thus predetermined will not vary with load variations up to the maximum capacity of the converter. By various types of wave forms, I mean that the ordinary type of wave form, commonly known as the sine wave, can be produced as well as the so-called "saw-tooth Wave or the so-called fiattop wave, it being generally known in the art that waves of these different types are especially suitable for different applications of converters.

It is to be understood that the appended claims are to be accorded a range of equivalents commensurate in scope with the advance made over the prior art.

I claim:

1. Acurrent converting system comprising a direct current source, and means for converting said direct current to alternating current; said means including an electrical circuit comprising said direct current source, a commutator divided into a plurality of segments electrically insulated from one another and electrically connected in pairs, a rotatable brush for successively engaging said segments, an electrical connection between said brush and one side of said direct current source, and a transformer having a mid-point tap electrically connected to the other side of said direct current source and divided into a plurality of sections equal in number on each side of said mid-point tap, electrical connections from one group of said plurality of segments of said commutator joining said segments in pairs to different sections of said transformer on one side of said mid-point tap, and electrical connections from another group of said plurality of segments of said transformer joining said segments in pairs to different sections of said transformer on the other side of said mid-point tap.

2. A current converting system comprising a direct current source, means for supplying alter- 4 nating current from said source including transformer having a mid-point tap connected, to one side of said source, a commutator divided into a plurality of segments, and a commutator brush for engaging said segments and connected to the other side of said source, and means for distributing the current in predetermined quantities and at predetermined intervals including leads from electrically paired segments of said commutator to spaced taps on one side of said transformer, and leads from other electrically paired segments of said commutator to spaced taps on the other side of said mid-point tap of said transformer.

3. In a current converting system, a transformer having a mid-point tap and a plurality of taps dividing the transformer into a plurality of sections taps on each side of said mid-point tap, a commutator divided into a plurality of segments, electrical connections between electrically paired segments of said commutator and said section taps on one side of said mid-point tap of said transformer, and electrical connections between other electrically paired segments and said section taps on the other side of said midpoint tap of said transformer.

4. In a current converting system, a transformer having a mid-point tap and a plurality of taps on each side of said mid-point tap dividing said. transformer into a plurality of section taps on each side of the center thereof, a commutator divided into two sets of segments grouped opposite to one another, electrical connections between segments of each set to group the segments of each set in pairs, electrical connections between electrically paired segments of one set to the section taps of said transformer on one side of the mid-point tap thereof, and electrical con nections between electrically paired segments of the other set and the section taps of said transformer on the other side of said mid-point tap.

5. A method of supplying alternating current from a direct current source and of distributing the current in predetermined quantities at predetermined time intervals, said method consisting of causing current alternately to flow through one side of a transformer toward the center thereof in sections of the transformer and to flow through the other side of the transformer toward the center thereof in sections of the transformer.

6. A method of supplying alternating current from a direct current source and for allotting the current in predetermined quantities and at pre determined time intervals, said method consisting of causing current successively to flow through one-half of a transformer and then sections of said one-half of the transformer always in a direction toward the center of the transformer, then successively to flow through the other half of the transformer and then through sections of said other half of the transformer in a direction always toward the center of the transformer.

FENTON F. HUTCHINSON. 

